Method of sealing a galvanic cell



1965 R. CARMICHAEL ETAL 3,223,559

METHOD OF SEALING A GALVANIC CELL Filed D60. 19. 1961 INVENTORS ROBERTCARMICHAEL JAMES SOUTHWORTH,JR.

BY 6 L Q 144% ATTOR/V y 3,223,559 METHOD OF SEALXN G A GALVANIC CELLRobert Carmichael, Lakewood, and James Southworth,

31:, Rocky River, Ohio, assiguors to Union Carbide Corporation, acorporation of New York Filed Dec. 19, 1961, Ser. No. 160,620 3 Claims.(Cl. 136-175) This invention relates to a seal closure for a cylindricalgalvanic cell container having at least one open end and moreparticularly to a method for applying such a seal closure. The sealclosure is particularly suitable for sealing a galvanic cell containerof the type employing an alkaline electrolyte.

A novel method for sealing an alkaline galvanic cylindrical cellcontainer is disclosed in United States Patent No. 3,069,489, issued onDecember 18, 1959, one of the joint inventors of the subject inventionbeing also one of the inventors of the above-referred invention. Thegalvanic cell closure disclosed in the patent is achieved by radicallycompressing under a high external radial force an L shaped hard plasticgasket which is interposed between a container and a cover therefor.When this radial force is applied, the container is reduced in diameterand the gasket is compressed radially against the outside diameter ofthe cover thus forming a leak-proof seal by virtue of a high residualradial force which is exerted outwardly by the gasket against thecontainer. By utilizing a hard plastic gasket having very low cold flow,the residual outward radial force is inherently the end result of theexternal radial force which is applied, and it is this residual forcewhich acts radially to the axis of the container and which provides aneffective seal closure.

A nylon, consisting of a hexamethylene diammonium adipate polymer suchas that commercially available under the trademark Zytel is thepreferred material for use as the seal gasket.

The actual method for obtaining a radial seal is dis closed to consistof positioning the gasket and cover on a step of a shouldered cellcontainer or by placing such elements on top of the contents or" astraight-sided cell container, and subsequently pushing or forcing thecell container with the gasket and cover in place through a die, therebydrawing down the cell container around the gasket and cover. Thisoperation must be skillfully done, otherwise an undesirable vertical oraxial component of force may be produced in the seal closure.Furthermore, if non-uniform loads are used on the cell in forcing thecontainer through the die, this can be detrimental to the quality of thecell since it is possible that these forces could cause the bottomradius of a thin walled cell container to be pushed into a rather sharpcorner, thereby causing a dimensional change of the cell which couldaffect the quality and operational ability of the cell. Moreover, anyexcessive pressures can damage the contents of the cell, and there iseven the possibility that the bottom of the container could be ruptured.If a misalignment occurs by any force in such a method it wouldjeopardize the radial seal effectiveness.

It is therefore the principal object of this invention to provide animproved process for applying a radial seal closure to a cylindricalgalvanic cell container.

Another object of the invention is to provide such a radial seal closurewithout impairing the quality of the cell or its contents.

Broadly stated, the objects of the invention are accomplished byaligning a cupped galvanic cell container fitted with a gasket and coverin an apparatus so that when the apparatus is actuated, a spring with apredetermined rate exerts a uniform pressure on the gasket and cover inorder to restrain them from displacement in the vertical direction itedStates Patent 3,223,559 Patented Dec. 14, 1965 during the period when ahigh external radial force is applied to the container thereby deformingit and producing the radial seal.

In order that the invention can be more readily understood, an apparatusfor effecting the closure which embodies the principles of the inventionis shown in the drawing, wherein:

FIG. 1 is a partially sectioned elevational view of the apparatus with agalvanic cell container in position prior to radial sealing;

FIG. 2 is an end view of the collet of the apparatus of FIG. 1; and

FIG. 3 is a sectional view taken along plane 33 of FIG. 2.

Referring now to the drawing and particularly to FIGS. 1 and 3, theapparatus comprises an annular collet 10 having a closed end 12 save foran aperture 14 in its center. The lower portion of the collet 10 has atapered surface 16 which tapers outwardly from about the center of thecollet 10 to a maximum diameter at a segmental face end 18. The collet10 is positioned within a compatibly shaped recess 20 provided in acollet cam ring 22. Between the end of the collet 10 and the top of therecess 20 a spring 24 is located.

As shown in FIG. 1, a cupped galvanic cell container 26 which is to beradially sealed is positioned directly beneath the collet 10 manually,semi-automatically or by automatic means. The cell container 26 issupported by a platen 28. A collet support ring 30 is used as an aid inpositioning and aligning the galvanic cell container 26 during theradial sealing; it also serves as a stop for the segmental face end 18of the collet 10 to slide on when radial pressure is applied by thecollet cam ring 22. A pressure pad 32 is located within the collet 10and is held in place by a travel screw 34. The travel screw 34 hasthreads 36 at one end which are screwed into a corresponding tapped hole38 in the pressure pad 32.

Referring now in particular to FIGS. 2 and 3, it will be be seen thatthe collet 10 is divided into a plurality of partially collapsiblesegments 40 which are formed by slots 42. Apertures 44 are provided atthe end of the slots 42 to aid this inward deflection of the segments40. The entire circumference of the cell container 26 is supported bythe segments 40.

In the operation of providing a radial seal to a galvanic cell container26, it is necessary to initially set up the apparatus for the particulargalvanic cell container 26 to be radially sealed. The travel screw 34 isused to adjust the relative position of the collet 10 with respect tothe collet cam ring 22. With the spring 24 exerting a force against thecollet 10 and the pressure pad 32, an hexagonal head 46 of the travelscrew 34 is rotated to either advance the collet 10 further into thecompatibly shaped recess 20 of the collet cam ring 22, or to release thespring force on the collet 10 and the pressure pad 32 therebywithdrawing the collet 10 from the compatibly aligned recess 29 of thecollet cam ring 22. When the travel screw 34 is set up for a particularrun it acts as a guide and as a limit stop for the collect cam ring 22.After the initial set-up is completed, the galvanic cell container 26together with a gasket 48 and cover 50 is aligned beneath the apparatus.The cell container 26 may be either a straight-sided one or a shoulderedcontainer as depicted in FIG. 1. Also the hard plastic gasket 48 isgenerally L shaped but it can be other than L shaped to suit the sealingof differently shaped cell containers. When a punch press slide (notshown) carrying the upper assembly of the apparatus travels downward thesegmental face end 18 of the collet 10 rests on the face of the colletsupport ring 30; the collet cam ring 22 continues its downward motionand causes the collet segments 40 to move in radially and reduce thediameter of the container 26 thereby radially squeezing the gasket 48between the rigid cell cover 50 and container 26. During this action thespring 24 is compressed and aplies a pressure on the pad 32 which inturn holds the cover 50 and gasket 48 in proper alignment with thecontainer 26. When the press releases its forces on the upward strokethe collet 10 is returned to its normal position by the action of thespring 24 and travel screw 34. It is to be appreciated that the springrestrains the gasket and cover from any vertical displacement andeliminates the build up of vertical or axial components of forces in theclosure while the radial seal is applied. This basic method of making aradial squeeze closure can also be produced by the action of a doubleslide press thus eliminating theneed for a collet support ring 30. Inone cycle of such a press the inner slide would actuate and control thevertical movement of the collet 10 and pressure pad 32 assembly so thatin a downward dwell position it holds the cover and gasket in place inthe container 26, whereupon the second or outer slide would move downwith the cam ring 22 attached and cause the collect segments 40 to movein radially and produce the desired radial squeeze seal. The upwardstroke of the press would release all pressures, eject the cellcontainer from the apparatus, and free the container for horizontalejection.

To test the effectiveness of the invention in preventing and eliminatingthe vertical component of the external radial force, a quarter-inchdiameter steel sphere was interposed between an empty galvanic cellcontainer (made from .010 inch sheet stock) and the platen of theapparatus; a radial seal was then applied to the cell container. Afterthe radial seal was formed, the container was inspected to determine ifany noticable dents or marks were formed in the bottom of the cellcontainer. No marks or dents were found, thus indicating that anyvertical component of the radial force and any other forces built up ina vertical axis direction is either negligible r practicallynon-existent when a radial seal closure is made by the practice of thesubject invention.

What is claimed is:

1. A method of radially sealing a galvanic cell, said cell comprising acell container, 2. cover therefor and an electrolyte therein; saidmethod comprising interposing between the inner wall of said cellcontainer and said cover a gasket of a hard dielectric plastic-likematerial which is resistant to cold flow, and radially compressing saidgasket between said cover and said cell container wall while restrainingany vertical displacement of said gasket and said cover; said radialcompression being effected by applying a relatively large sealing force,perpendicular to the axis of said cell and having substantially novertical component, in the horizontal plane of said cover and saidgasket so that said container is primarily squeezed radially about aperipheral zone near said cover, the restraining of said gasket and saidcover being effected by applying a relatively small axial force directlyon said cover; said radial compression being effected by positioningsaid container with said gasket and said cover in place beneath anannular-shaped collet having a plurality of segments and squeezing saidsegments so that said segments partially collapse and draw saidcontainer in and around said cell cover and said gasket in compressivestress.

2. The method of claim 1 wherein said gasket is made of a nylonconsisting of a hexamethylene diammonium adipate polymer.

3. The method of claim 2 wherein said gasket is generally an annular Lshaped gasket.

References Cited by the Examiner UNITED STATES PATENTS 1,932,136 10/1933Hole 113-59 2,516,546 7/1950 Brown 113-59 2,803,691 8/1957 Herbert etal. 136-133 2,922,832 1/1960 Gottschall et al. 136133 3,069,489 12/1962Carmichael et al. 136-175 WINSTON A. DOUGLAS, Primary Examiner.

JOHN R. SPECK, JOHN H. MACK, Examiners.

1. A METHOD OF RADIALLY SEALING A GALVANIC CELL, SAID CELL COMPRISING ACELL CONTAINER, A COVER THEREFOR AND AN ELECTROLYTE THEREIN; SAID METHODCOMPRISING INTERPOSING BETWEEN THE INNER WALL OF SAID CELL CONTAINER ANDSAID COVER A GASKET OF A HARD DIELECTRIC PLASTIC-LIKE MATERIAL WHICH ISRESISTANT TO COLD FLOW, AND RADIALLY COMPRESSING SAID GASKET BETWEENSAID COVER AND SAID CELL CONTAINER WALL WHILE RESTRAINING ANY VERTICALDISPLACEMENT OF SAID GASKET AND SAID COVER; SAID RADIAL COMPRESSIONBEING EFFECTED BY APPLYING A RELATIVELY LARGE SEALING FORCE,PERPENDICULAR TO THE AXIS OF SAID CELL AND HAVING SUBSTANTIALLY NOVERTICAL COMPONENT, IN THE HORIZONTAL PLANE OF SAID COVER AND SAIDGASKET SO THAT SAID CONTAINER IS PRIMARILY SQUEEZED RADIALLY ABOUT APERIPHERAL ZONE NEAR SAID COVER, THE RESTRAINING OF SAID GASKET AND SAIDCOVER BEING EFFECTED BY APPLYING A RELATIVELY SMALL AXIAL FORCE DIRECTLYON SAID COVER; SAID RADIAL COMPRESSION BEING EFFECTED BY POSITIONINGSAID CONTAINER WITH SAID GASKET AND SAID COVER IN PLACE BENEATH ANANNULAR-SHAPED COLLET HAVING A PLURALITY OF SEGMENTS PARTIALLY COLLAPSEAND DRAW SAID CONTAINER IN AND AROUND SAID CELL COVER AND SAID GASKET INCOMPRESSIVE STRESS.